Conventionally, paints with inorganic or organic dyes or pigments or bright materials such as aluminum flakes and mica have been used to give colors to various materials such as fiber, building material and coating material, or reflect therefrom ultraviolet and infrared rays, or achieve further improvement of visual quality and feeling thereof.
Recently, with user's diversified taste and tendency to higher quality, there are increasing demands on graceful and quality fiber structures which have color tones varying with the point of view and higher chromas. In such a situation, many attempts are carried out to obtain a fiber structure which produces a color relying upon no coloring matter such as dye or pigment, but physical phenomena such as optical reflection, interference, diffraction and scattering, and a fiber structure which produces a brighter color relying upon the synergistic effect of coloring due to a coloring matter and coloring due to physical phenomena.
By way of example, JP 43-14185 and JP-A 1-139803 disclose coated-type composite fibers with iridescence which are made of two or more resins having different optical refractive index. A journal of the Textile Machinery Society of Japan (Vol. 42, No. 2, pp. 55-62, published in 1989 and Vol. 42, No. 10, pp. 60-68, published in 1989) describes laminated photo-controllable polymer films for producing colors by optical interference, wherein a film with anisotropic molecular orientation is interposed between two polarizing films.
JP-A 59-228042, JP-B2 60-24847, and JP-B2 63-64535 disclose fabrics with iridescence conceived, e.g. from a South American morpho-butterfly which is well-known by its bright color tone varying with the point of view. JP-A 62-170510 and JP-A 63-120642 disclose structures which produce interference colors due to recesses with a predetermined width formed on the surface of the fibers. Both references describe that formed structures are fast and permanent in color due to no use of dyes and pigments.
However, the composite fibers as disclosed in JP 43-14185 and JP-A 1-139803 cannot produce transparent bright colors since the optical thickness (=thickness of a coating layer .times.refractive index) is not always uniform, and the coloring region is not wide, but limited. The laminated photo-controllable polymer films as described in the journal of the Textile Machinery Society of Japan cannot produce colors with sufficient brightness, and are difficult to form in fine fibers or minute chips or fragments at a low manufacturing cost. The fabrics and structures as disclosed in JP-A 59-228042, JP-B2 60-24847, JP-B2 63-64535, JP-A 62-170510, and JP-A 63-120642 are practically very difficult to provide desired coloring effect.
For solving such inconveniences, U.S. Pat. No. 5,407,738 and U.S. Pat. No. 5,472,798 propose structures which produce bright and permanent colors having tones varying with the point of view by optical reflection and interference. The teachings of U.S. Pat. No. 5,472,798 are hereby incorporated by reference. Moreover, JP-A 7-195603 proposes a structure which reflects ultraviolet ray and/or infrared ray.
In order to manufacture a coloring structure having optical reflection and interference as disclosed, e.g. in U.S. Pat. No. 5,472,798, however, the number of combinable polymers is small which form alternate lamination and have the refractive-index ratio of 1.1 or more, causing a problem of less variety of combination. Further, despite a great advantage of a possible reduction in the number of layers for achieving higher reflectivity, the flowability of the combinable polymers is not always sufficient, which makes very difficult uniform and stable manufacturing of alternate lamination of films with small thickness (e.g. 0.08 .mu.m) except part of the combinable polymers. Furthermore, the combinable polymers, which are not in general use, are high in cost.
It is, therefore, an object of the present invention to provide a fiber structure having reflection and interference of visible radiation or reflection of ultraviolet or infrared radiation, with easy manufacturing process and reduced manufacturing cost. Another object of the present invention is to provide a textile using such fiber structure.